Dry etching is a technology for carrying out thin film etching by using of plasmas. Gases have two characteristics in the case of existing in the form of plasmas: on one hand, the chemical activities of the gases in the form of plasmas are much higher than those of the gases in a normal state, therefore selecting a proper gas according to different etched materials can make it reacting with the materials more quickly, so as to realize the purpose of etching removal; on the other hand, the plasmas can also be guided and accelerated by an electric field so as to accumulate a certain energy, and atoms of the etching object material are struck out while the plasmas strike the surface of the etching object, thus achieving the purpose of realizing etching by physical energy transfer.
In a process of producing a display panel, a plurality of medium layers on a glass substrate need to be etched by dry etching, and a step of “conversion processing” needs to be performed once after each medium layer is etched. The “conversion processing” is used for creating a clean environment for etching for another medium layer. The conventional “conversion processing” generally comprise steps of turning off a radiofrequency module in a dry etching equipment and stopping introducing a reaction gas used for etching a previous medium layer into a reaction chamber, and meanwhile, performing vacuumizing processing on the reaction chamber by a vacuum pump.
After the “conversion processing” is finished, a reaction gas required for etching a next medium layer is introduced into the reaction chamber, and the radiofrequency module is turned on again to excite the reaction gas to form into plasmas, so as to etch the next medium layer.
However, when the “conversion processing” is performed, introducing the gas into the reaction chamber is stopped, and the radiofrequency module is turned off, thus the plasmas in the reaction chamber are suddenly extinguished. At this moment, particulate pollutants suspending in the plasmas may fall onto the glass substrate, and thus cause pollution to subsequent manufacture procedures, which results in defectiveness of the display panel.